Insulation detection device and method for multi-path photovoltaic string, controller, storage medium and photovoltaic system

Abstract

The invention provides an insulation detection device and method for a multi-path photovoltaic string, a controller, a storage medium and a photovoltaic system. The insulation detection device comprises a positive electrode detection module, a negative electrode detection module and a negative electrode sampling module, the positive electrode detection module comprises a plurality of positive electrode detection units and positive electrode sampling units corresponding to the positive electrode detection units, the first end of each positive electrode detection unit is connected with the output end of the corresponding photovoltaic string, and the second end of each positive electrode detection unit is grounded; each positive electrode sampling unit is used for collecting electric data of the corresponding positive electrode detection unit; the first end of the cathode detection module is connected with the cathode of the DC bus, and the second end is grounded. The cathode sampling module is used for collecting electric data of the cathode detection module. According to the insulation detection device, the situation that when the output voltages of the photovoltaic strings are inconsistent, the booster circuit with the high output voltage cuts off the voltage output of the photovoltaic strings with the low output voltage, and consequently insulation faults cannot be effectively detected can be avoided, and the insulation detection accuracy is improved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic system technology, and in particular to an insulation detection device, method, controller, storage medium, and photovoltaic system for multi-channel photovoltaic strings. Background Technology

[0002] Insulation testing of photovoltaic strings is a key step in ensuring the safe and stable operation of photovoltaic systems. It can effectively prevent leakage risks caused by string insulation failure, prevent short circuits and arc discharges caused by insulation degradation, reduce equipment damage such as junction box burnout and cable aging, and extend the service life of photovoltaic systems.

[0003] To detect insulation faults in photovoltaic systems, existing technologies typically install insulation detection circuits on the DC bus side of each photovoltaic string to detect whether an insulation fault has occurred in each string. However, this method has poor detection accuracy, and often individual photovoltaic strings fail to detect insulation faults. Summary of the Invention

[0004] This invention provides an insulation detection device, method, controller, storage medium, and photovoltaic system for multi-channel photovoltaic strings, to solve the problem of poor accuracy in insulation detection of multi-channel photovoltaic strings in the prior art.

[0005] In a first aspect, embodiments of the present invention provide an insulation detection device for multiple photovoltaic strings, applied to a photovoltaic system, the photovoltaic system including multiple photovoltaic strings and a boost unit corresponding to each photovoltaic string; the output terminal of each photovoltaic string is connected to the low-voltage side of the corresponding boost unit, and the high-voltage side of each boost unit is connected to the DC bus of the photovoltaic system; The insulation detection device includes: a positive electrode detection module, a negative electrode detection module, and a negative electrode sampling module; The positive electrode detection module includes multiple positive electrode detection units and a positive electrode sampling unit corresponding to each positive electrode detection unit. The first end of each positive electrode detection unit is connected to the output end of the corresponding photovoltaic string, and the second end of each positive electrode detection unit is grounded. Each positive electrode sampling unit is used to collect the electrical data of the corresponding positive electrode detection unit. The first terminal of the negative electrode detection module is connected to the negative electrode of the DC bus, and the second terminal of the negative electrode detection module is grounded. The negative electrode sampling module is used to collect electrical data from the negative electrode detection module.

[0006] Secondly, embodiments of the present invention provide an insulation detection method for multi-channel photovoltaic strings, characterized in that it is applied to the insulation detection device for multi-channel photovoltaic strings described in the first aspect above, the method comprising: The negative electrode detection module is turned on, and each positive electrode detection unit is turned on individually. The electrical data of each positive electrode detection unit when it is turned on is acquired and used as the first electrical data; and the electrical data of the negative electrode detection module when it is turned on is used as the second electrical data. For any given photovoltaic string, the insulation test results of each photovoltaic string are determined based on the first and second electrical data corresponding to that photovoltaic string.

[0007] Thirdly, embodiments of the present invention provide a controller, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the insulation detection method for the multi-channel photovoltaic string as described in any possible implementation of the second aspect above.

[0008] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the insulation detection method for multi-channel photovoltaic strings as described in any possible implementation of the second aspect above.

[0009] Fifthly, this embodiment provides a photovoltaic system, which includes: an insulation detection device for multiple photovoltaic strings as described in the first aspect above and a controller as described in the third aspect.

[0010] This invention provides an insulation detection device, method, controller, storage medium, and photovoltaic system for multi-channel photovoltaic strings. The photovoltaic system includes multiple photovoltaic strings and corresponding boost units for each string. The output terminals of each photovoltaic string are connected to the low-voltage side of the corresponding boost unit, and the high-voltage side of each boost unit is connected to the DC bus of the photovoltaic system. The insulation detection device includes a positive electrode detection module, a negative electrode detection module, and a negative electrode sampling module. The positive electrode detection module includes multiple positive electrode detection units and corresponding positive electrode sampling units. The first terminal of each positive electrode detection unit is connected to the output terminal of the corresponding photovoltaic string, and the second terminal of each unit is grounded. Each sampling unit collects electrical data from its corresponding unit. The first terminal of the negative electrode detection module is connected to the negative terminal of the DC bus, and the second terminal is grounded. The sampling module collects electrical data from the negative electrode detection module. In the aforementioned insulation detection device, the positive detection module of each channel bypasses the boost unit and is directly connected to the output terminal of the photovoltaic string. This avoids the situation where, when the output voltages of the various photovoltaic strings are inconsistent, the photovoltaic string with the higher output voltage cuts off the voltage output of the photovoltaic string with the lower output voltage, thus preventing the photovoltaic string from effectively detecting insulation faults. This improves the accuracy of insulation detection for multiple photovoltaic strings. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the structure of an existing insulation testing device for multi-channel photovoltaic strings; Figure 2 This is a schematic diagram of the structure of the insulation detection device for multi-channel photovoltaic strings provided in an embodiment of the present invention; Figure 3 This is a flowchart illustrating the insulation detection method for multi-channel photovoltaic strings provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the insulation detection device for multi-channel photovoltaic strings provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the controller provided in an embodiment of the present invention. Detailed Implementation

[0013] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0014] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0015] Figure 1 A schematic diagram of an insulation detection device for a multi-channel photovoltaic string in the prior art is shown, as follows: Figure 1 As shown, the insulation detection device is applied to a photovoltaic system, which includes multiple photovoltaic strings 10, a boost unit 20 corresponding to each photovoltaic string 10, and a DC bus BUS. Each photovoltaic string 10 has its output terminal connected to the low-voltage side of its corresponding boost unit 20, and the high-voltage side of each boost unit 20 is connected to the DC bus BUS, which can be connected to the subsequent inverter circuit.

[0016] Specifically, such as Figure 1As shown, taking photovoltaic string 1 as an example, the boost unit 20 includes a first capacitor C11, a second capacitor C12, an inductor L1, a switch Q1, and a diode D1. The first capacitor C11 is connected between the positive and negative terminals of the low-voltage side of the boost unit 20. The inductor L1 is connected to the positive terminal of the low-voltage side of the boost unit 20, and its negative terminal is connected to the positive terminal of the diode D1 and the collector of the switch Q1. The emitter of the switch Q1 is connected to the negative terminal of the low-voltage side of the boost unit 20. The negative terminal of the diode D1 and the first terminal of the second capacitor C12 are both connected to the positive terminal of the high-voltage side of the boost unit 20, and the second terminal of the second capacitor C12 is connected to the negative terminal of the high-voltage side of the boost unit 20.

[0017] Currently, when performing insulation fault detection on photovoltaic strings 10, the insulation detection circuit is usually set at the output terminal of the boost unit of each photovoltaic string. By detecting the voltage between the positive and negative terminals of the boost unit output terminal and ground, it is determined whether there is an insulation fault in the photovoltaic string.

[0018] However, as Figure 1 As shown, when the output voltages of multiple photovoltaic strings are different, when the one with the higher output voltage reaches the DC bus BUS+, the output of the photovoltaic string with the lower output voltage will be cut off due to the effect of the diode in the boost unit. As a result, when the insulation detection circuit at the back end performs insulation fault detection on the photovoltaic string with the higher output voltage, it will actually detect the photovoltaic string with the higher output voltage. Therefore, the insulation fault of the photovoltaic string with the lower output voltage will not be detected or will be detected incorrectly.

[0019] To address the aforementioned issues, this embodiment provides an insulation detection device for multiple photovoltaic strings. Figure 2 This embodiment shows a schematic diagram of the insulation detection device for multi-channel photovoltaic strings. Figure 2 As shown, the insulation detection device includes: a positive electrode detection module, a negative electrode detection module, and a negative electrode sampling module; The positive electrode detection module includes multiple positive electrode detection units and a positive electrode sampling unit corresponding to each positive electrode detection unit. The first end of each positive electrode detection unit is connected to the output end of the corresponding photovoltaic string, and the second end of each positive electrode detection unit is grounded. Each positive electrode sampling unit is used to collect the electrical data of the corresponding positive electrode detection unit. The first terminal of the negative electrode detection module is connected to the negative electrode of the DC bus, and the second terminal of the negative electrode detection module is grounded. The negative electrode sampling module is used to collect electrical data from the negative electrode detection module.

[0020] In this embodiment, the photovoltaic string is a power generation unit formed by multiple photovoltaic panels connected in series, outputting low-voltage direct current. The boost unit is used to boost the voltage of the photovoltaic string; specifically, it can be a DC-DC converter. The positive electrode detection unit provides collectable and analyzable electrical signals for insulation detection on the positive side of each photovoltaic string. The positive electrode sampling unit collects electrical data from the positive electrode detection unit, which may include voltage and current data. The negative electrode detection module provides collectable and analyzable electrical signals for insulation detection on the negative side of the photovoltaic string. The negative electrode sampling module collects electrical data from the negative electrode detection module, which may include voltage and current data. The DC bus is a common DC line connecting the high-voltage sides of all boost units, used for centralized power transmission, and connected to the subsequent inverter circuit. The insulation detection proposed in this embodiment detects the insulation performance between the photovoltaic string and ground, preventing risks such as leakage and short circuits due to insulation failure.

[0021] Specifically, each positive electrode detection unit can be turned on and off independently to perform insulation testing on a single photovoltaic string, avoiding interference from the insulation test results of other photovoltaic strings.

[0022] In this embodiment, the positive electrode detection unit may include a switch and a resistor. By controlling the gate voltage of the switch, the conduction state of the switch is changed, thereby realizing the turn-on and turn-off of the positive electrode detection unit.

[0023] As can be seen from the above embodiments, in the above insulation detection device, the positive detection module of each channel skips the boost unit and is directly connected to the output terminal of the photovoltaic string. This can avoid the situation where the output voltage of each photovoltaic string is inconsistent, and the photovoltaic string with a higher output voltage cuts off the voltage output of the photovoltaic string with a lower output voltage, causing the photovoltaic string to be unable to effectively detect insulation faults. This achieves the effect of improving the insulation detection accuracy of multiple photovoltaic strings.

[0024] In one possible implementation, the positive electrode detection unit includes a first switch and a first resistor; The first switch and the first resistor are connected in series between the first and second terminals of the positive electrode detection unit.

[0025] In this embodiment, the first switch controls the on / off state of the corresponding positive electrode detection unit, and is only turned on when performing insulation testing on that photovoltaic string, so as to avoid long-term connection affecting the normal operation of the photovoltaic string and affecting the insulation testing results of other photovoltaic strings. The first switch can be a relay, a MOSFET, etc.

[0026] In this embodiment, the positive detection unit may also include a self-resetting fuse to prevent excessive ground fault current.

[0027] The first resistor is used for voltage division and current limiting. The voltage across its terminals can be used to deduce the current and insulation resistance values ​​in the circuit, thus enabling the determination of insulation faults. The resistance value of the first resistor can be determined based on the output voltage level of the photovoltaic string. The higher the output voltage of the photovoltaic string, the larger the resistance value of the first resistor, to prevent excessive current flowing through the positive electrode detection unit in the event of an insulation fault.

[0028] Specifically, when performing insulation testing on a certain photovoltaic string, the first switch of that photovoltaic string is closed, while the first switches of other photovoltaic strings are open. The voltage or current value across the first resistor is collected through the positive sampling unit. If the voltage value is less than the first preset voltage threshold, or the sampled current value is greater than the preset current threshold, then the photovoltaic string is determined to have a fault.

[0029] Preferably, the insulation detection device may further include a controller and a first optocoupler. The controller controls the opening and closing of the first switch through the first optocoupler. Since there is no electrical connection between the controller and the first switch, and information is transmitted only through optical signals, the isolation between the high-voltage side and the low-voltage side can be achieved, avoiding high-voltage interference or damage to the controller.

[0030] As can be seen from the above embodiments, the positive electrode detection unit in this embodiment adopts a structure of a first switch and a first resistor connected in series, which has significant practicality and flexibility. The setting of the first switch can realize the controllable on / off switching of the detection circuit, conducting only during detection, avoiding affecting the insulation detection results of other photovoltaic strings, and reducing unnecessary energy loss. The first resistor, as a reference element with known parameters, provides a stable reference for electrical data sampling, ensuring that the sampled value can accurately reflect the relationship between the circuit current and the insulation resistance, reducing detection errors caused by fluctuations in component parameters. In addition, this series structure is simple and easy to implement, requiring no complex circuit design, which helps to reduce the production cost and maintenance difficulty of the device.

[0031] In one possible implementation, the electrical data includes voltage values; The positive sampling unit is used to detect the voltage value across the first resistor of the positive detection unit.

[0032] As can be seen from the above embodiments, this embodiment uses voltage values ​​as insulation fault detection data, which is easier to acquire and process with high precision and low cost compared to current signals, and has stronger anti-interference capabilities, thereby improving the reliability of the entire detection system.

[0033] In one possible implementation, the electrical data includes a current value; the positive sampling unit is a current transformer used to detect the current value flowing through the positive detection unit.

[0034] In one possible implementation, the negative electrode detection module includes a second switch and a second resistor; The second switch and the second resistor are connected in series between the first and second terminals of the negative electrode detection module.

[0035] In this embodiment, the second switch is used to control the on / off state of the corresponding negative electrode detection module, and it is only turned on during insulation detection to avoid long-term connection affecting the normal operation of the photovoltaic string. The second switch can be a relay, a MOSFET, etc.

[0036] The second resistor is used for voltage division and current limiting. The voltage across its terminals can be used to deduce the current and insulation resistance values ​​in the circuit, thus enabling the determination of insulation faults. The resistance value of the second resistor can be determined based on the output voltage level of the photovoltaic string. The higher the output voltage of the photovoltaic string, the larger the resistance value of the second resistor, to prevent excessive current flowing through the positive electrode detection unit in the event of an insulation fault.

[0037] In this embodiment, the negative electrode detection module may also include a self-resetting fuse to prevent excessive ground fault current.

[0038] Specifically, during insulation testing of each photovoltaic string, the second switch is closed, and the voltage or current value across the second resistor is collected through the negative sampling module. If the voltage value is less than the second preset voltage threshold, or the sampled current value is greater than the preset current threshold, then the photovoltaic string is determined to have a fault.

[0039] Preferably, the insulation detection device may further include a second optocoupler. The controller controls the on / off state of the second switch through the second optocoupler. Since there is no electrical connection between the controller and the second switch, and information is transmitted only through optical signals, the isolation between the high-voltage side and the low-voltage side can be achieved, avoiding high-voltage interference or damage to the controller.

[0040] In one possible implementation, the electrical data includes a voltage value; the negative sampling module is used to detect the voltage value across the second resistor of the negative detection module.

[0041] In one possible implementation, the positive terminal of the boost unit includes a diode; the insulation detection device further includes a third switch connected in parallel across the diode of the boost unit.

[0042] Specifically, when performing insulation testing on a certain photovoltaic string, the third switch of that photovoltaic string can be controlled to close to avoid the situation where the diodes of that photovoltaic string are cut off by the output voltage of other photovoltaic strings when the output voltages of multiple photovoltaic strings are inconsistent.

[0043] See Figure 3 The diagram illustrates the implementation flowchart of the insulation detection method for multi-channel photovoltaic strings provided by an embodiment of the present invention. This method is applied to the controller of the aforementioned insulation detection device, and is described in detail below: S101: Control the negative electrode detection module to turn on, and control each positive electrode detection unit to turn on individually; S102: Obtain the electrical data when each positive electrode detection unit is turned on, and use it as the first electrical data; and obtain the electrical data when the negative electrode detection module is turned on, and use it as the second electrical data; S103: For any photovoltaic string, based on the first electrical data and the second electrical data corresponding to that photovoltaic string, determine the insulation test results of each photovoltaic string.

[0044] In this embodiment, the controller individually activates each positive electrode detection unit and acquires the first electrical data corresponding to each positive electrode detection unit. The first electrical data can be current data and voltage data. Simultaneously, when performing insulation testing on the photovoltaic string, the controller activates the negative electrode detection module and acquires the second electrical data corresponding to the negative electrode detection module. The second electrical data includes current data and voltage data.

[0045] When the electrical data is current data, the controller acquires the first current data and the second current data. If the first current data is greater than the preset current threshold, or the second current data is greater than the preset current threshold, it indicates that the leakage current of the photovoltaic string is large and there is an insulation fault.

[0046] As can be seen from the above embodiments, this embodiment constructs a distributed insulation detection architecture by setting up an independent positive electrode detection unit, a negative electrode detection module, and a sampling module for each photovoltaic string. It directly connects the positive electrode detection unit between the output terminal of each photovoltaic string and ground, bypassing the boost unit, thus avoiding the influence of the boost unit's operating state or inconsistent output voltages of the photovoltaic strings during detection. When a photovoltaic string experiences leakage current to ground due to an insulation fault, the corresponding positive electrode detection unit can be controlled to conduct, cooperating with the always-conducting negative electrode detection module to form an independent detection loop. By collecting the electrical data of each unit, the insulation status of the loop can be accurately reflected, effectively avoiding signal interference problems in traditional common bus detection and preventing missed detection of insulation faults in multiple photovoltaic strings. The separate conduction mode ensures that the detection data of each photovoltaic string is independent and non-overlapping, avoiding signal confusion caused by multiple simultaneous conductions, and improving the uniqueness and accuracy of the data.

[0047] In one possible implementation, the specific implementation process of S101 includes: The second switch of the negative electrode detection module is closed, and the first switch of each positive electrode detection unit is closed individually.

[0048] Specifically, the controller controls the second switch of the negative electrode detection module to close, and controls the first switches of each positive electrode detection unit to close individually. Then, it detects the states of the first and second switches. If the first switch changes from an open to a closed state, it waits for a first preset time before acquiring the electrical data collected by the corresponding positive electrode sampling unit. If the second switch changes from an open to a closed state, it waits for the same first preset time before acquiring the electrical data collected by the corresponding negative electrode sampling module, thus avoiding the impact of instantaneous fluctuations on data accuracy. The first preset time can be 30ms to 60ms.

[0049] In this embodiment, the method provided further includes: The system acquires ambient temperature and humidity data of the photovoltaic (PV) string environment and adjusts the insulation testing cycle accordingly. Furthermore, temperature and humidity data are negatively correlated with the insulation testing cycle. That is, when the PV string is in a high-temperature and high-humidity environment, the insulation testing cycle is shortened to ensure timely detection of insulation faults.

[0050] Specifically, the temperature and humidity data mentioned above can be the weighted sum of the ambient temperature and humidity of the environment in which the photovoltaic string is located.

[0051] In one possible implementation, the first electrical data includes a first voltage value; the second electrical data includes a second voltage value. The specific implementation process of S103 includes: If the absolute value of the first voltage value is less than the first preset voltage threshold, or the absolute value of the second voltage value is less than the first preset voltage threshold, then the photovoltaic string is determined to have an insulation fault.

[0052] In one possible implementation, the specific implementation process of S103 includes: The first voltage difference is obtained by subtracting the first voltage value of the previous insulation test from the first voltage value of the current insulation test. If the first voltage difference is detected to be less than the preset voltage difference N times consecutively, it is predicted that a positive electrode insulation fault will occur in the photovoltaic string. The preset voltage difference is less than zero.

[0053] In this embodiment, based on historical data analysis, if the voltage value of a certain photovoltaic string continues to drop, even if the first voltage value is not less than the first preset voltage threshold, it can be determined that there is a potential insulation fault. Therefore, it is necessary to generate insulation fault warning information in advance.

[0054] Similarly, the specific implementation process of S103 also includes: The second voltage difference is obtained by subtracting the second voltage value of the previous insulation test from the second voltage value of the current insulation test. If the second voltage difference is detected to be less than the preset voltage difference N times consecutively, it is predicted that the photovoltaic string will soon experience a negative electrode insulation fault, where the preset voltage difference is less than zero.

[0055] As can be seen from the above embodiments, this embodiment provides a clear and operable standard for insulation fault determination based on the threshold judgment logic of the first voltage value and the second voltage value. By setting a first preset voltage threshold, the abstract insulation state is transformed into an intuitive voltage value comparison, simplifying the judgment process, reducing algorithm complexity, and facilitating rapid execution by the controller. This embodiment can effectively identify the leakage risk caused by excessively low insulation resistance: when the first voltage value or the second voltage value is lower than the threshold, the fault is directly determined, avoiding the delay caused by complex calculations and improving the fault response speed.

[0056] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0057] The following are device embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.

[0058] Figure 4 A schematic diagram of the insulation detection device for multi-channel photovoltaic strings provided in an embodiment of the present invention is shown. For ease of explanation, only the parts related to the embodiment of the present invention are shown, and are described in detail below: like Figure 4 As shown, the insulation testing device 100 for multi-channel photovoltaic strings includes: The conduction control module 110 is used to control the negative electrode detection module to conduct and to control each positive electrode detection unit to conduct individually. The electrical data acquisition module 120 is used to acquire electrical data when each positive electrode detection unit is turned on, and use it as the first electrical data; and the electrical data when the negative electrode detection module is turned on, and use it as the second electrical data; The insulation detection module 130 is used to determine the insulation detection results of each photovoltaic string based on the first electrical data and the second electrical data corresponding to that photovoltaic string.

[0059] In one possible implementation, the first electrical data includes a first voltage value; the second electrical data includes a second voltage value; the insulation detection module 130 is specifically used for: If the absolute value of the first voltage value is less than the first preset voltage threshold, or the absolute value of the second voltage value is less than the first preset voltage threshold, then the photovoltaic string is determined to have an insulation fault.

[0060] Figure 5This is a schematic diagram of the controller provided in an embodiment of the present invention. Figure 5 As shown, the controller 5 in this embodiment includes a processor 50, a memory 51, and a computer program 52 stored in the memory 51 and executable on the processor 50. When the processor 50 executes the computer program 52, it implements the steps in the insulation detection method embodiments of the various photovoltaic strings described above, for example... Figure 3 Steps S101 to S103 are shown. Alternatively, when the processor 50 executes the computer program 52, it implements the functions of each module in the above-described device embodiments.

[0061] For example, the computer program 52 may be divided into one or more modules / units, which are stored in the memory 51 and executed by the processor 50 to complete the present invention. The one or more modules / units may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program 52 in the controller 5.

[0062] The controller 5 can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server. The controller 5 may include, but is not limited to, a processor 50 and a memory 51. Those skilled in the art will understand that... Figure 5 This is merely an example of controller 5 and does not constitute a limitation on controller 5. It may include more or fewer components than shown, or combine certain components, or different components. For example, the controller may also include input / output devices, network access devices, buses, etc.

[0063] The processor 50 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0064] The memory 51 can be an internal storage unit of the controller 5, such as a hard disk or memory of the controller 5. The memory 51 can also be an external storage device of the controller 5, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the controller 5. Furthermore, the memory 51 can include both internal storage units and external storage devices of the controller 5. The memory 51 is used to store the computer program and other programs and data required by the controller. The memory 51 can also be used to temporarily store data that has been output or will be output.

[0065] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0066] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0067] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0068] In the embodiments provided by this invention, it should be understood that the disclosed devices / controllers and methods can be implemented in other ways. For example, the device / controller embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0069] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0070] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0071] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the insulation detection method embodiments for each of the above-described multi-channel photovoltaic strings. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0072] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. An insulation testing device for multi-channel photovoltaic strings, characterized in that, This technology is applied to photovoltaic systems, which include multiple photovoltaic strings and corresponding boost units for each photovoltaic string. The output terminals of each photovoltaic string are connected to the low-voltage side of the corresponding boost unit, and the high-voltage side of each boost unit is connected to the DC bus of the photovoltaic system. The insulation detection device includes: a positive electrode detection module, a negative electrode detection module, and a negative electrode sampling module; The positive electrode detection module includes multiple positive electrode detection units and a positive electrode sampling unit corresponding to each positive electrode detection unit. The first end of each positive electrode detection unit is connected to the output end of the corresponding photovoltaic string, and the second end of each positive electrode detection unit is grounded. Each positive electrode sampling unit is used to collect the electrical data of the corresponding positive electrode detection unit. The first terminal of the negative electrode detection module is connected to the negative electrode of the DC bus, and the second terminal of the negative electrode detection module is grounded. The negative electrode sampling module is used to collect electrical data from the negative electrode detection module.

2. The insulation detection device for multi-channel photovoltaic strings according to claim 1, characterized in that, The positive electrode detection unit includes a first switch and a first resistor; The first switch and the first resistor are connected in series between the first and second terminals of the positive electrode detection unit.

3. The insulation detection device for multi-channel photovoltaic strings according to claim 2, characterized in that, The electrical data includes voltage values; The positive sampling unit is used to detect the voltage value across the first resistor of the positive detection unit.

4. The insulation detection device for multi-channel photovoltaic strings according to claim 1, characterized in that, The negative electrode detection module includes a second switch and a second resistor; The second switch and the second resistor are connected in series between the first and second terminals of the negative electrode detection module.

5. The insulation detection device for multi-channel photovoltaic strings according to claim 4, characterized in that, The electrical data includes voltage values; the negative electrode sampling module is used to detect the voltage value across the second resistor of the negative electrode detection module.

6. An insulation testing method for multi-channel photovoltaic strings, characterized in that, The insulation testing device applied to the multi-channel photovoltaic string according to any one of claims 1 to 5, the method comprising: The negative electrode detection module is turned on, and each positive electrode detection unit is turned on individually. The electrical data of each positive electrode detection unit when it is turned on is acquired and used as the first electrical data; and the electrical data of the negative electrode detection module when it is turned on is used as the second electrical data. For any given photovoltaic string, the insulation test results of each photovoltaic string are determined based on the first and second electrical data corresponding to that photovoltaic string.

7. The insulation detection method for multi-channel photovoltaic strings according to claim 6, characterized in that, The first electrical data includes a first voltage value; the second electrical data includes a second voltage value; For any given photovoltaic string, based on the first and second electrical data corresponding to that photovoltaic string, the insulation test results for each photovoltaic string are determined, including: If the absolute value of the first voltage value is less than the first preset voltage threshold, or the absolute value of the second voltage value is less than the first preset voltage threshold, then the photovoltaic string is determined to have an insulation fault.

8. A controller comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the insulation detection method for the multi-channel photovoltaic string as described in any one of claims 6 to 7.

9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the insulation detection method for the multi-channel photovoltaic string as described in any one of claims 6 to 7.

10. A photovoltaic system, characterized in that, It includes the insulation detection device for the multi-channel photovoltaic string as described in any one of claims 1 to 5 and the controller as described in claim 8.

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